In recent years, research on a high-density optical disk is growing in popularity. There has been a particular problem that fluctuation in size of a record mark is caused by variation in such recording conditions as a recording light quantity of a light beam to be emitted to an optical disk, a recording magnetic field strength of an externally applied magnetic field to be applied to a magneto-optical disk, and the like, thereby preventing uniform recording and making it difficult to realize high-density recording.
Further, recording sensitivity varies for each optical disk, which is due to variation occurred during manufacture. Namely, seen from the side of an optical recording device, each optical disk shows different tendencies in terms of an optimum recording condition whereby a record mark can be formed into a proper shape and an optimum recording condition according to the position of a radius. Further, recording sensitivity is not simply unique to each optical disk but also changeable according to variation in an environmental temperature. Therefore, it is necessarily to examine optimum recording conditions for an optical recording device for each optical disk loaded and for each change in the environmental temperature. In reality, the optimum recording conditions are obtained by performing test writing with respect to a plurality of test domains, each of which has a radius in a different position.
Meanwhile, methods of further increasing a capacity of an optical disk include land-groove recording. Conventionally, recording with respect to an optical disk was performed using either a land or a groove alone. In contrast, the land-groove recording is a method in which both the land and groove are used as recording tracks so as to improve recording density.
A land-groove recording-use medium is considered to have not much difference in characteristics of recording layers because films are deposited on the land and the groove simultaneously. However, a problem is that a difference may occur in optimum recording conditions even in the case where a land and a groove adjacent to each other are compared, which is due to (i) variation in a ratio of a land width to a groove width, (ii) a difference in thermal conductivity from the land to the groove and vice versa, and (iii) others.
Against this problem are proposed solutions shown below.
First, Japanese Unexamined Patent Publication No. 16965/1997 (Tokukaihei 9-16965 published on Jan. 17, 1997) discloses a method of setting recording power in which, in test writing areas provided in both a land and a groove, test writing is performed with respect to both the land and groove, thereby setting appropriate recording power for the land and groove, respectively.
Next, the published Japanese Patent No. 3024120 (Date of Patent: Jan. 21, 2000) discloses a method of recording and reproducing optical information in which identifiers indicative of recording conditions (light intensity, track pitch, the width and depth of a groove, etc.) are provided, and a recording condition for land and that for groove are separately provided. Particularly, it is disclosed that, in order to shorten time or simplify circuitry, correlation between a land and a groove is previously obtained, thereafter obtaining a recording condition for either one of the land and the groove by performing test writing, while, for the other, a recording condition is obtained based on the correlation.
However, in the method disclosed in the above publication 16965/1997, it is a problem that, while performing test writing with respect to the both land and groove and obtaining respective optimum recording conditions, an optical recording device is required to suspend for a certain time the operation of recording or reproduction that should be performed in accordance with a user's instruction. Therefore, possible frequent occurrence of such suspension of the operation inevitably impairs a data transfer rate, namely, it impairs the performance of the optical recording device.
Further, in the method disclosed in the Japanese Patent No. 3024120, the setting of a recording light quantity is more accurate in a track on which test writing is performed than in a track for which a recording light quantity was obtained according to the correlation. Therefore, in the case where the setting of a recording light quantity is carried out more than once, the accuracy in the setting of a light quantity is likely to lose a good balance.